xCrazyEightx

Hi there!
I just bought myself a 2008 RX-8!
I Love it, and its also broken, WHAT A SURPRISE!
Honestly we expected it to be at least a little messed up. It was sold for $1,100 because the old owners were moving and needed to get rid of it. The car had issues, namely that the battery was bad and WHEN CHARGED the car was extreamly lacking in power, would sputter and struggle, and eventually the engine would just shut off. The people who sold it knew it had bad ignition coils and a dead battery, which was fine because me and my brother intended to change the coils, battery, plugs, and wires anyways. And so we did (and also used Seafoam because the car had been sitting for quite a while) aaaaaaaaand... the engine is still having issues. Which led us to finding out that the o2 sensor was malfunctioning as well. So we changed that out as well... aaaand the car is still having troubles, BUT now starts up nice and smooth! My fear was that it had bad apex seals but the pressure the compression test came back with 91 and 95 psi... supposedly it needs to be above 75, but ideally is supposed to be 110 and 115. While not as good as it should be, still not as bad as we feared it would be. Me and my brother are running out of ideas at this point what could be causing my RX-8 to lose power. Hence why I am here, I need help.

Car has 106,000 miles
New Battery
New Ignition coils
New Spark plugs
New O2 sensor
Seafoam to help clean engine

Issues
Car has no power. Starts up just fine but cant reach more than like 30 mph in the test run we did. Engine struggles and sometimes dies. Running VERY RICH.
We have a few engine codes:
P0301 Cylinder 1 Misfire Detected
U0121 Lost Communication With Anti-Lock Break System Control Module
P2097 Post Catalyst Fuel Trim System Too Rich Bank 1
P0172 Bank 1 System Too Rich
P0443 Evaporative Emission System Purge Control Valve Circuit

Any assistance with this would be much appreciated! And since I can only post in the new members forum, If you are seeing this and thinking "That doesn't go there!" I will be copying it over to a more appropriate section as soon as I can, don't yell at me

Loki

iTrader: (1)

91 and 95 psi @ 250 rpm are still failing compression numbers, but the results make no sense. You should have 6 numbers @ XXX rpm. Sounds like you used a regular piston compression tester. I woiuld 't take those results too seriously.

Are the spark plugs conmected to the correct coils?
Are the injectors all in their correct places (i.e. primaries aren't accidentally wired to the secondary signal)?
Is the car fully stock?

Needless to say, don't drive it like this, you will destroy the cat. In fact check the cat for clogging since it has a history of poor ignition.

TeamRX8

iTrader: (25)

Probably because the were using a piston compression gauge.

xCrazyEightx

6 numbers huh? hmm... Well I must have been using the wrong compression tester then. Which one would you recommend exactly?

ALSO
Spark Plus - As far as we know, yes they are connected correctly. We checked several times out of fear that we did it wrong.
Injectors - I'm new to cars, you mean like fuel injectors? I don't know if we checked on those but Ill look into it.
Is the car stock - to the best of my available knowledge, yes. No aftermarket modding.

What are the odds it may be an issue with the computer or the fuel injectors?

dannobre

iTrader: (3)

Os it REALLY slow... it could be in limp mode??

xCrazyEightx

See, thats what i thought. Tried to see if we could reset it. didn't seem to change anything.

CaymanRotary

P0301, Misfires usually solved by changing out wires, plugs and coils. If you already did this, just reset the code and see if it returns. You will know when it misfires because you will see the CEL flash while you drive.
U0121: Could be a wire unplugged or it could mean you need a new ABS module. I would have a mechanic solve this for you unless you know your way around ABS systems.
P2097: Could be related to the misfire. Other reasons could be failing front O2 sensor, MAF sensor or a clogged cat. Best to try the 20 brake pedal stomp trick to reset your fuel trims. If this doesn't work, clean your MAF with a good MAF cleaner and reinstall.
P0172: Same as above
P0443: Just dealt with this issue for a friend of mine. its either the solenoid which is attached just under the upper intake manifold or its the hoses on top of the manifold. You should see this pretty easily. because its a very short hose that comes out and goers back into the UIM.

Loki

iTrader: (1)

Does it pass 4000rpm in any gear? If not, that's limp mode. If it does, but struggles that's not limp mode. Limp mode is most commonly caused by bad OMP conmection or internal OMP failure. The OMP codes are not always readable by all code scanners, they're specific to Mazda.



It's not the computer, computers don't fail this way. If it is getting bad info from a sensor, find which sensor.

What are the fuel trims? It sounds to me like injectors are miswired. If the fuel trims are all far in the egative and it is still running rich, definitely check the injector wiring.

I don't think the O2 sensor would do this, because that is what is telling you it is rich in the first place. Unless it is reading rich but is not actually rich. The computer should detect that kind of failure and throw a different O2 code though. It has diagnostics for this kind of thing.